German engineers test silent propellers to save marine life without losing speed
German researchers are launching a new project to tackle one of the ocean’s loudest problems. Ship propellers create massive noise that disrupts marine life, El.kz reports citing Interesting Engineering.
This interference breaks the communication, feeding, and mating patterns of marine mammals.
Now, a team at HAW Kiel is developing new propeller designs to silence the seas.
The state of Schleswig-Holstein is fueling this effort with a €390,000 grant. The project, named MinKav, officially kicked off on January 1, 2026.
Researchers aim to cut underwater noise without losing vessel efficiency or speed. This balance is critical for the future of global shipping.
Science of cavitation
Propeller noise starts with a physical phenomenon called cavitation. Pressure drops sharply on the suction side of a spinning blade. This causes water to vaporize and form tiny bubbles.
When pressure rises again, these bubbles collapse with violent force. This process creates loud, impulsive sounds that travel for miles.
Leonie Föhring is leading the doctoral research at HAW Kiel’s Institute for Shipbuilding and Maritime Technology.
She uses a cavitation tunnel, high-speed cameras, and underwater microphones to study these bubbles. Her goal is to make the invisible visible and the silent audible.
“The loud impulse occurs at the moment the bubble collapses. Its volume depends on how rapidly the process takes place,” Föhring explains.
“We now want to find out whether it’s even possible to slow this collapse down—and how propellers would need to be designed to achieve that.”
Modern commercial ships currently use custom-designed propellers.
However, underwater noise has rarely been a priority for engineers. Prof. Jörn Kröger, the project lead, believes this must change to meet upcoming environmental limits.
“We need practical methods that allow noise reduction to be routinely integrated into propeller design,” Kröger notes.
He wants to ensure these changes do not cause “significant losses in efficiency or speed.”
Current solutions often require ships to slow down to remain quiet. This tradeoff leads to longer travel times and higher costs for shipping companies.
Föhring and Kröger are using computer flow simulations to find a better way.
They want to protect marine species while maintaining energy efficiency for climate protection.
Fixing the global fleet
The project includes expertise from JASCO-ShipConsult, a specialist in ship acoustics.
Shipbuilding engineer Dr. Dietrich Wittekind sees a major gap in current maritime research.
He notes that international teams have studied low-frequency noise for 20 years.
“Despite many measurements, we still lack a fundamental understanding of the mechanism responsible for the high noise levels, and therefore the basis for making ships quieter,” Wittekind says.
“This is precisely where MinKav begins: It is the first project to systematically analyze the root causes and develop concrete solutions for significant noise reduction through propeller measures.”
The findings could apply to both new builds and existing vessels.
This offers a real chance to reduce noise pollution across the world’s oceans. The MinKav project will run through December 31, 2028.
Its success could redefine how the world’s fleet moves through the water.
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